U.S. patent application number 15/368868 was filed with the patent office on 2017-03-23 for additives for fuels and oils comprising functionalised diblock copolymers.
This patent application is currently assigned to Infineum International Limited. The applicant listed for this patent is Infineum International Limited. Invention is credited to Christopher J. Kay, Kenneth Lewtas, Peter Scott, Giles W. Theaker, Carl Waterson, Peter M. Wright.
Application Number | 20170081458 15/368868 |
Document ID | / |
Family ID | 48669826 |
Filed Date | 2017-03-23 |
United States Patent
Application |
20170081458 |
Kind Code |
A1 |
Waterson; Carl ; et
al. |
March 23, 2017 |
ADDITIVES FOR FUELS AND OILS COMPRISING FUNCTIONALISED DIBLOCK
COPOLYMERS
Abstract
Concentrates containing specific functionalised diblock
copolymers serve as effective additives for improving the cold flow
behaviour of fuels and oils, the copolymers being derived from a
terminally-unsaturated intermediate polymer obtained via a
metallocene process involving hydrogen.
Inventors: |
Waterson; Carl; (Wrexham,
GB) ; Lewtas; Kenneth; (Wantage, GB) ; Scott;
Peter; (Coventry, GB) ; Kay; Christopher J.;
(Coventry, GB) ; Theaker; Giles W.; (Abingdon,
GB) ; Wright; Peter M.; (Mountainside, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineum International Limited |
Abingdon |
|
GB |
|
|
Assignee: |
Infineum International
Limited
Abingdon
GB
|
Family ID: |
48669826 |
Appl. No.: |
15/368868 |
Filed: |
December 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13936539 |
Jul 8, 2013 |
9540583 |
|
|
15368868 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08F 297/02 20130101;
C10N 2030/02 20130101; C09D 153/025 20130101; C10L 2230/14
20130101; C10L 1/236 20130101; C10L 1/1963 20130101; C10L 2250/04
20130101; C10L 2270/026 20130101; C10N 2020/02 20130101; C07C 15/02
20130101; C10N 2030/08 20130101; C10M 145/02 20130101; C08F 4/65925
20130101; C10L 1/143 20130101; C10N 2020/04 20130101; C10M 145/14
20130101; C08F 295/00 20130101; C10L 1/16 20130101; C10L 10/14
20130101; C10M 2205/06 20130101; C10M 2209/084 20130101; C10M
143/12 20130101; C10L 10/16 20130101; C08F 4/65912 20130101; C10L
1/1658 20130101; C10M 2205/022 20130101; C10N 2020/011 20200501;
C10L 1/165 20130101; C08G 81/021 20130101; C10M 2205/04 20130101;
C10M 2205/022 20130101; C10M 2205/04 20130101; C10M 2205/022
20130101; C10M 2209/084 20130101; C08F 110/02 20130101; C08F
2500/17 20130101; C09D 153/025 20130101; C08L 53/025 20130101; C08L
91/00 20130101 |
International
Class: |
C08F 297/02 20060101
C08F297/02; C10M 145/14 20060101 C10M145/14; C10M 143/10 20060101
C10M143/10; C10M 143/12 20060101 C10M143/12; C10L 1/196 20060101
C10L001/196; C10L 1/16 20060101 C10L001/16 |
Claims
1. A process for manufacture of a functionalised diblock copolymer
comprising 2 polymeric blocks wherein: (i) the first block consists
of a chain of ethylenic structural traits, optionally interrupted
by one or more structural units derived from 1-alkene co-monomers
higher than ethylene, and (ii) the second Hock comprises a chain of
structural units derived from one or more
.alpha.,.beta.--unsaturated monomers selected from styrene,
substituted styrene, acrylate, methacrylate and diene compounds,
and wherein said first and second Hocks of the copolymer are
terminally joined by means of the following structural linkage:
##STR00022## wherein each R group independently represents an alkyl
or aryl group and R' represents hydrogen or an alkyl group, and
wherein the aromatic ring substituent joined to the second block is
positioned meta or para to the aromatic ring substituent joined to
the first block; the process comprising the following steps: a) in
a first step, polymerising ethylene, and optionally one or more
1-alkene co-monomers higher than ethylene, in the presence of a
metallocene catalyst system to form a first polymer block, being a
chain consisting of ethylenic structural units optionally bearing
pendent alkyl groups originating from 1-alkene comonomer(s), the
reaction being carried out in solution at a temperature of at least
50.degree. C. in the presence of a compound of the formula (I):
##STR00023## in a reaction vessel pressurised with hydrogen gas,
wherein, in the course of the reaction, the compound (I) is
terminally incorporated onto the first polymer block resulting in
the formation of a terminally unsaturated intermediate of the
formula (II): ##STR00024## b) in a second step, recovering the
intermediate (II) from the reaction mixture of the first step; and
c) in a third step, reacting the intermediate (II) at its terminal
double bond in a subsequent polymerisation reaction to form a
second polymer block, so yielding a diblock polymer of the
structure defined above.
2. The process of claim 1, wherein the compound (I) has the
structure: ##STR00025## wherein each R group independently
represents an alkyl group having from 1 to 4 carbon atoms.
3. The process of claim 2, wherein the compound (I) has the
structure: ##STR00026##
4. The process of claim 1, wherein R' represents n-butyl.
5. The process of claim 1, wherein, in the compound of formula (I),
the aromatic ring substituent joined to the second block is
positioned meta to the substituent joined to the first block.
6. The process of claim 1 wherein the third step c) is an anionic
polymerisation reaction, wherein the terminal double bond of the
intermediate of formula (II) is reacted with a metallating reagent
to form an anion which initiates polymerisation therefrom upon the
addition of one or more .alpha.,.beta.--unsaturated monomers
selected from styrene, substituted styrene, acrylate, methacrylate
and diene compounds.
7. The process of claim 6, wherein the metallating agent is an
alkyl metal compound R'M and the intermediate of the formula (II)
has the structure: ##STR00027## wherein each R group independently
represents an alkyl group having from 1 to 4 carbon atoms; and
wherein, in the course of the third reaction step c), the alkyl
group R' of the alkyl metal compound inserts onto the
less-substituted carbon of the double bond, giving rise to a
reactive anionic intermediate having the structure of the formula
(III): ##STR00028## wherein alkyl represents the inserted alkyl
group originating from the alkyl metal compound, .sup.(-)
represents the metallated carbanionic site from which the anionic
polymerisation of the third reaction step thereafter proceeds, and
M(.sup.+) represents the metal cation originating from the metal M
of the alkyl metal compound.
8. The process of claim 6 wherein the metallating reagent comprises
n-butyl lithium or sec-butyl lithium.
9. The process of claim 6 wherein the intermediate of the formula
(II) has the structure ##STR00029## and the metallating reagent
comprises n-butyl lithium.
10. The isolated intermediate compound of the formula (II):
##STR00030## wherein each R group independently represents an alkyl
or aryl group, and wherein the aromatic ring substituent
--C(R).dbd.CH.sub.2 is positioned meta or para to the substituent
joined to the first block.
11. The anionic intermediate of the formula (III): ##STR00031##
wherein each R group independently represents an alkyl or aryl
group and wherein the aromatic ring substituent
--C.sup.(-)(R)--CH.sub.2(R') is positioned meta or para to the
aromatic ring substituent joined to the first block; wherein R'
represents an alkyl group and M.sup.+ represents a metal cation,
and C.sup.(-) represents a metallated carboanionic site.
12. The intermediate of claim 10 wherein each R group independently
represents an alkyl group having from 1 to 4 carbon atoms.
13. The intermediate of claim 12 wherein each R group independently
represents a methyl group.
14. The intermediate of claim 13 wherein R' represents n-butyl.
15. The intermediate of claim 14 wherein the other aromatic ring
substituent is positioned meta to the substituent joined to the
first block.
16, The intermediate of claim 15 wherein the first block consists
of a polyethylene chain.
17. The intermediate of claim 16 wherein the first block has a
number average molecular weight (Mn), as measured by GPC against
polystyrene standards, in the range of 500 to 20000 g
mol.sup.-1.
18. The intermediate of claim 11 wherein each R group independently
represents an alkyl group having from 1 to 4 carbon atoms.
19. The intermediate of claim 18 wherein each R group independently
represents a methyl group.
20. The intermediate of claim 19 wherein R' represents n-butyl.
21. The intermediate of claim 20 wherein the other aromatic ring
substituent is positioned meta to the substituent joined to the
first block.
22. The intermediate of claim 21 wherein the first block consists
of a polyethylene chain.
23. The intermediate of claim 22 wherein the first block has a
number average molecular weight (Mn), as measured by GPC against
polystyrene standards, in the range of 500 to 20,000 g
mol.sup.-1.
24. The anionic intermediate (III) of claim 11, wherein M.sup.+
represents a lithium cation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No.
13/936,539, filed Jul. 8, 2013.
[0002] The present invention concerns performance-enhancing
additives for fuels and oils, the additives comprising
functionalised diblock copolymers having specific: structures,
together with a process for making such copolymers and other
aspects of the invention as hereinafter described.
[0003] Base fuels and oils, i.e. the fuels and oils produced by
processing of crude oil or other liquid or gaseous petroleum
feedstocks, or by processing of biologically-derived material such
as vegetable or animal oils and fats, or by synthetic means, are
the basis for modem finished commercial fuels and oils, but by
themselves typically lack the combination of specific properties
for a specific application that is demanded by modern standards,
legislation and/or consumer requirements. It has become commonplace
in industry to enhance the properties of base fuels and oils by
treatment with additives augmenting the relevant properties, so
that they meet all the needs of the application in question.
[0004] In particular, many base fuels and oils naturally contain,
as elements of their complex mixed compositions, one or more
n-alkyl-, iso-alkyl- or n-alkenyl-substituted compounds, especially
one or more n-alkanes, exhibiting a tendency to crystallise from
the base fuel or oil in cold storage or use, thereby adversely
affecting the cold flow behaviour of the base fuel or oil. As a
result, transportation of the fuel or oil through the often complex
distribution and vehicle systems for such products becomes
problematic. Such problems include reduced flow and the blockage of
filters, or even blockage of pipes where the crystallisation is so
extensive that gelling of the fuel or oil occurs. In oils, as well
as filter blockages, these gels can also create "channelling" of
the oil where oil is drawn off initially, but the yield stress is
high enough to leave most of the oil in the sump, leading to air
being channelled and the vehicle failing by "air binding" of the
pump. There is an ongoing need for solutions to this problem, and
additives play an important role in improving the cold flow
properties of such fluids, particularly in colder regions of the
world where storage or use at cold ambient temperatures may be
required for substantial periods.
[0005] A number of solutions have been proposed over the years to
improve cold flow properties of fuels and oils, and commercial
additives used today typically include various low molecular-weight
ethylene-vinyl ester copolymers. Such copolymers tend to have
random copolymeric structures, and are often used in blended
mixtures to meet particular target performance needs.
[0006] On occasions, block copolymers wherein the blocks have been
separately polymerised and then joined by coupling reactions
between heteroatomic functional groups have been postulated. Such
heteroatomic couplings are however open to cleavage by hydrolysis
or other reactions, leading to degradation of the copolymer and
loss of function.
[0007] Over time various other additive solutions have been
proposed to improving the cold flow properties of fuels and oils,
and these include wax anti-settling additives that typically
comprise monomeric (rather than polymeric) compounds that serve to
keep crystallised material better dispersed in the fuel. A variety
of other monomeric or polymeric solutions have also been
proposed.
[0008] Historically, the blend recipes of the base fuels or oils
have sometimes been altered to incorporate more of the lower fuel
or oil fractions in order to dilute the problematic compounds and
provide a lighter base material with lower tendency towards cold
flow problems. However, such an approach frequently suffers from
adverse manufacturing economics from the viewpoint of refinery
operations.
[0009] A need remains in the art for additives capable of
effectively improving the cold flow properties of fuels and oils,
and the present invention is particularly directed to the provision
of new copolymeric materials having advantages as additives for
this purpose.
[0010] The polymer art offers various types of copolymers. For
example, previous work has demonstrated that, depending on the
conditions, ethylene can be copolymerised with styrene and
p-methylstyrene to form either copolymers in which the monomers are
interspersed in the growing monomer chain, or materials having a
polyethylene chain terminated with a single styrene or
p-methylstyrene unit (for the latter, see the publication by J. Y.
Dong and T. C. Chung entitled "Synthesis of Polyethylene Containing
a Terminal p-Methylstyrene Group: Metallocene-Mediated Ethylene
Polymerisation with a Consecutive Chain Transfer Reaction to
p-Methylstyrene and a Hydrogen", reported in Macromolecules 2002,
35, 1622-1631). In particular, in the latter reference Chung et al.
suggest the preparation of polyethylene which is substantially
terminally functionalised by the addition of a single unit of
styrene or p-methylstyrene via a proposed chain-transfer reaction,
effected by certain metallocene catalysts in the presence of
hydrogen. The resulting materials are thereafter postulated to be
suitable for subsequent reaction, for example by metallation of the
methyl group of p-methylstyrene, to prepare diblock copolymers. No
industrial applications for such materials are suggested.
Furthermore, the molecular weights reported for the functionalised
polyethylenes produced by Chung et al. are higher than those of
polymers typically used for industrial applications such as
additives for improving the cold flow properties of many oils, and
much higher than those of polymers used for improving the cold flow
properties of fuels, especially fuels such as middle distillate
fuels like diesel fuel.
[0011] Chung et al. also do not describe the terminal
chain-transfer reaction of polyethylene with co-monomers other than
styrene or p-methylstyrene. Furthermore, they do not postulate the
preparation of a polyethylene chain with a more reactive terminal
group that is more easily processed into industrially-useful
chemicals, and do not address how that goal might be achieved.
[0012] EP-A-0 522 729 concerns an ethylene polymer cross linking
composition using an organic peroxide as a cross-linking agent and
a second compound as cross linking auxiliary compound, The process
necessarily proceeds via a radical mechanism and relies on the
peroxide. The resulting product is extensively cross-linked, and no
reactive intermediate can be isolated as it proceeds.
[0013] The present invention concerns additives which comprise new
functionalised diblock copolymers of the structure hereinafter
defined. The additives are useful in fuels and oils, in particular
for improving the cold flow behaviour of a fuel or oil composition
derived from one or more petroleum, biological or synthetic sources
and containing one or more n-alkyl- or iso-alkyl or
n-alkenyl-substituted compounds, especially one or more n-alkanes,
exhibiting a tendency to crystallise from the base fuel or oil in
cold storage or use and thereby adversely affecting the cold flow
behaviour of the base fuel or oil.
[0014] As used in this specification, the term "n-alkyl, iso-alkyl
or n-alkenyl substituted compounds" collectively includes those
compounds which are n-alkanes, those compounds which are
iso-alkanes, those compounds which are n-alkenes, and those
compounds containing n-alkyl, iso-alkyl or n-alkenyl groups, which
exhibit a tendency to crystallise from fuel or oil at low
temperatures. N-alkanes and iso-alkanes and n-alkenes on the one
hand, and other compounds bearing n-alkyl, iso-alkyl or n-alkenyl
substituents on the other hand, are typically present within base
to fuels and oils, although the relative proportions and
distributions of individual compounds differ from source to source.
However, the invention described herein is particularly effective
in relation to fuels and oils containing one or more n-alkanes,
especially one or more long chain n-alkanes such as those having at
least 20 carbon atoms, preferably at least 24 carbon atoms, which
show a particular tendency to crystallise from the fuel or oil at
low temperatures. Most of these fuels or oils will contain a range
of such molecules, typically containing from 10 to 30 carbon atoms,
although wider and narrower ranges are commonly seen.
[0015] The present invention further concerns fuel and oil
compositions comprising the additives of the invention, and a
method of improving the cold flow behaviour of a fuel or oil
composition. In addition, the present invention concerns the new
functionalised diblock copolymers of the structure hereinafter
defined, along with their use to improve the cold flow behaviour of
a fuel or oil composition, a process for their manufacture and the
associated novel chemical intermediates.
[0016] FIG. 1 is a typical .sup.1H NMR spectrum of intermediate
compound (II) as produced by the process of the invention, as
hereinafter detailed.
[0017] In a first aspect therefore, the present invention provides
an additive concentrate comprising a functionalised diblock
copolymer in admixture with an organic liquid miscible with fuel or
oil, the copolymer comprising 2 polymeric blocks wherein: [0018]
(i) the first block consists of a chain of ethylenic structural
units, optionally interrupted by one or more structural units
derived from 1-alkene co-monomers higher than ethylene, and [0019]
(ii) the second block comprises a chain of Structural units derived
from one or more .alpha.,.beta.--unsaturated monomers selected from
styrene, substituted styrene, acrylate, methacrylate and diene
compounds, and wherein said first and second blocks of the
copolymer are terminally joined by means of the following
structural linkage:
##STR00001##
[0019] wherein each R group independently represents an alkyl or
aryl group and R' represents hydrogen or an alkyl group, and
wherein the aromatic ring substituent joined to the second block is
positioned meta or para to the aromatic ring substituent joined to
the first block.
[0020] In this specification, the word "terminal" when used in
relation to a polymer chain (or block) simply refers to the end of
the polymer chain (or block), and does not convey any additional
mechanistic requirement that the chain (or block) end in question
be the end at which the polymerisation reaction terminated.
References to "terminally" shall be construed analogously.
[0021] In the structural formulae recited in this specification, it
is also to be understood that any chiral centres are not intended
to imply the selective formation or use of specific enantiomers;
the materials of the invention should thus be taken to be racemic
mixtures.
[0022] In a second aspect, the present invention provides a fuel or
oil composition comprising: [0023] (i) a base fuel or oil derived
from one or more petroleum, animal, vegetable or synthetic sources,
the base fuel containing one or more n-alkyl-, iso-alkyl- or
n-alkenyl-substituted compounds exhibiting a tendency to
crystallise from the has fuel or oil in cold storage or use thereby
adversely affecting the cold flow behaviour of the base fuel or
oil, and [0024] (ii) the additive concentrate of the first aspect
of the invention, wherein the additive is present in the
composition in an amount sufficient to improve the cold flow
behaviour of the base fuel or oil during cold storage or use.
[0025] In a third aspect, the present invention concerns a method
of improving the cold flow behaviour of a fuel or oil composition
derived from one or more petroleum, animal, vegetable or synthetic
sources and containing one or more n-alkyl-, iso-alkyl- or
n-alkenyl-substituted compounds exhibiting a tendency to
crystallise from the base fuel or oil in cold storage or use
thereby adversely affecting the cold flow behaviour of the base
fuel or oil, the method comprising: [0026] (i) determining the cold
flow behaviour of the base fuel or oil in question and the
improvement that is required; [0027] (ii) determining the amount of
the additive concentrate of the first aspect necessary to effect
the desired improvement in cold flow behaviour; and [0028] (iii)
treating the base fuel or oil with that amount of the additive
concentrate of the first aspect.
[0029] In this specification, the term "cold storage or use" of a
fuel or oil refers to storage or use at temperatures below the
Cloud Point of the fuel or oil, i.e. below the temperature at
which, prior to treatment with the additive of the invention, the
n-alkyl, iso-alkyl or n-alkenyl-substituted compounds present in
that fuel or oil visibly begin to exhibit their tendency to
crystallise from the fuel or oil. The Cloud Point is a well-known
industry test, so-named because it observes the point at which the
previously-clear fuel becomes `cloudy` as fine crystals begin to
visibly form from the bulk medium.
[0030] The advantageous properties of the additive concentrate are
attributed to the nature of the diblock copolymer defined therein,
In particular, and without being bound to any particular theory, it
is believed that when present in the fuel or oil under cold storage
or use conditions the polyethylenic chain of the first block of a
copolymer molecule interacts with the growing crystal of n-alkyl-,
iso-alkyl- or n-alkenyl-substituted compounds (and particularly
n-alkane compounds) as they crystallise from the cold fuel or oil,
thereafter inhibiting further crystal growth. This interaction is
enabled by the geometry of polyethylenic sequences of the first
block aligning with segments of the n-alkyl, iso-alkyl or n-alkenyl
groups of the crystallising compounds. The second block of the
polymer provides the correct dispersibility within the fuel, and
provides steric hindrance to aid the blocking of further
crystallisation at crystal growth sites.
[0031] In a fourth aspect, the invention is the functionalised
diblock copolymer defined under any of the other aspects of the
invention.
[0032] It is essential for the efficacy of the additive that the
first block of the copolymer has a backbone chain of polyethylenic
structural units. Interrupting this chain of the first polymer
block with other structural units, such as an aromatic ring, which
introduce a backbone segment that does not approximate in geometry
to polyethylenic structural units, is unfavourable for performance
in this application and is not part of the invention. However, it
is permissible to incorporate in the backbone chain of the first
block a proportion of co-monomer units derived from 1-alkenes
higher than ethylene, such that the resulting polymer chain remains
an uninterrupted is sequence of saturated aliphatic carbon atoms,
the residual alkyl groups of the 1-alkene residues being borne as
saturated alkyl substituents pendant from the polymer chain.
[0033] It is likewise important that the first block of the
copolymer be terminally joined to the second block, so as to leave
the first block exposed for interacting with the growing crystals
in the fuel or oil. As such, it is important that the linkage
between the first and second blocks be positioned at the end of the
polymeric chain of the first block.
[0034] To achieve this terminal positioning of the linkage between
the first and second blocks, it is essential that the process by
which the copolymer is made be specific for terminal
functionalization of the first block. Equally, it is important that
the terminal functionalization formed on the first block be
sufficiently reactive to enable the subsequent formation of the
second block under process conditions that are industrially
practical, whilst at the same time not being so highly reactive
that unwanted side reactions occur to a significant extent.
[0035] The applicants have now found that, in the presence of
hydrogen, a metallocene-catalysed polymerisation reaction between
ethylene (and optionally higher 1-alkenes) and a compound of the
formula (I):
##STR00002##
wherein each R group independently represents an alkyl or aryl
group, and wherein the two aromatic ring substituents are
positioned meta or para to each other, results in a highly specific
reaction product being a terminally unsaturated intermediate
compound of the formula (II):
##STR00003##
wherein R is as defined above in relation to compound (I).
[0036] The applicants have found that compound (II) is, by virtue
of its terminal unsaturation, reactive towards subsequent reaction
steps, in particular the polymerisation of the second block, and
thus provides an industrially-useful starting point for further
reaction. In particular, it is more usefully reactive than a
pendant alkyl group towards metallation and subsequent anionic
polymerisation. However, surprisingly, the applicants have also
found that despite this terminal unsaturation, the compound (II) is
stable and can be isolated; and is also not prone to significant
spontaneous side reactions during its formation.
[0037] In particular, the applicants have found that despite
compound (I) being di-unsaturated, it is not prone to multiple
reaction with the growing polyethylene chains and does not give
rise to appreciable cross-linking, resulting in a high proportion
of the desired compound (II) being formed. The applicants have also
found that compound (I) is specific for terminal incorporation with
the first block, and does not appreciably incorporate within the
body of the growing polyethylenic chain. This lack of `in-chain`
(as opposed to terminal) incorporation is in contrast to the
reported tendency of the otherwise analogous material
di-vinylbenzene to also incorporate in-chain to an appreciable
extent, under similar reaction conditions with propylene, as
reported in Macromol. Rapid Commun. 2005, 26, 1936-1941.
[0038] With the benefit of knowledge of this aspect of the
invention, the applicants attribute this difference in specificity
for terminal reaction to the presence of the R substituents on the
vinyl groups of compound (I), which appear to distinguish its
reactivity from di-vinylbenzene under such conditions. As a result,
the compound (I) provides a favourable balance of reactivities to
enable the preparation of the intermediate (II) and the subsequent
copolymer.
[0039] The R substituents originating from compound (I) carry
through as structural features into the intermediate (II) and
thereafter, including further intermediates in the later processing
and into the final copolymer. Thus, whilst the presence of the R
substituents on the vinyl groups of compound (I) first appears to
specify a single, terminal insertion into the polyethylene chain,
the presence of the R substituent the remaining vinyl group in
compound (II) also serves to moderate the reactivity Of compound
(II), and favourably direct the subsequent polymerisation reaction,
particularly when this occurs through anionic polymerisation, where
the R group serves to create a stable tertiary carbanionic centre
during the metallation step. In the resulting block copolymer, the
structure linking the first and second blocks is exclusively
hydrocarbon in nature, and therefore not susceptible to hydrolysis
or other cleavage reactions that may affect linkages comprised of
heteroatomic functional groups such as ester or amides.
[0040] In a fifth aspect therefore, the invention is a process for
manufacture of a functionalised diblock copolymer comprising 2
polymeric blocks wherein: [0041] (i) the first block consists of a
chain of ethylenic structural units, optionally interrupted by one
or more structural units derived from 1-alkene co-monomer(s) higher
than ethylene, and [0042] (ii) the second block comprises a chain
of structural units derived from one or more
.alpha.,.beta.--unsaturated monomers selected from styrene,
substituted styrene, acrylate, methacrylate or diene compounds, and
wherein said first and second blocks of the copolymer are
terminally joined by means of the following structural linkage:
##STR00004##
[0042] wherein each R group independently represents an alkyl or
aryl group and R' represents hydrogen or an alkyl group, and
wherein the aromatic ring substituent joined to the second block is
positioned meta or para to the aromatic ring substituent joined to
the first block; the process comprising the following steps: [0043]
in a first step, polymerising ethylene, and optionally one or more
alkene co-monomers higher than ethylene, in the presence of a
metallocene catalyst system to form a first polymer block, being a
chain consisting of ethylenic structural units optionally bearing
pendent alkyl groups originating from 1-alkene comonomer(s), the
reaction being carried out in solution at a temperature of at least
50.degree. C. in the presence of a compound of the formula (I):
[0043] ##STR00005## in a reaction vessel pressurised with hydrogen
gas, wherein, in the course of the reaction, the compound (I) is
terminally incorporated onto the first polymer block resulting in
the formation of a terminally unsaturated intermediate of the
formula (II):
##STR00006## [0044] b) in a second step, recovering the
intermediate (II) from the reaction mixture of the first step; and
[0045] c) in a third step, reacting the intermediate (II) at its
terminal double bond in a subsequent polymerisation reaction to
form a second polymer block, so yielding a diblock polymer of the
structure defined above.
[0046] In the process aspect of the invention, step c) is
preferably an anionic polymerisation reaction, wherein the terminal
double bond of the intermediate of formula (II) is reacted with a
metallating reagent to form an anion which initiates polymerisation
therefrom upon the addition of one or more
.alpha.,.beta.--unsaturated monomers selected from styrene,
substituted styrene, acrylate, methacrylate and diene
compounds.
[0047] In a sixth aspect, the invention is the isolated
intermediate compound of the formula (II):
##STR00007##
wherein each R group independently represents an alkyl or aryl
group and R' represents hydrogen or an alkyl group, and wherein the
aromatic ring substituent C(R).dbd.CH.sub.2 is positioned meta or
para to the aromatic ring substituent joined to the first
block.
[0048] The third step c) of the process of the fifth aspect is
preferably an anionic polymerisation reaction, wherein the terminal
double bond of the intermediate of formula (II) is reacted with a
metallating reagent to form an anion which initiates polymerisation
therefrom upon the addition of one or more
.alpha.,.beta.--unsaturated monomers selected from styrene,
substituted styrene, acrylate, methacrylate and diene
compounds.
[0049] This preferred aspect of the process proceeds via the
conversion of the intermediate of the compound (II) into an anionic
intermediate. Thus, in a seventh aspect, the invention is the
anionic intermediate of the formula (III):
##STR00008##
wherein each R group independently represents an alkyl or aryl
group and wherein the aromatic ring substituent
--C.sup.(-)(R)--CH.sub.2(R') is positioned meta or para to the
aromatic ring substituent joined to the first block; wherein R'
represents an alkyl group and M.sup.+ represents a metal cation,
and C.sup.(-) represents a metallated carbanionic site.
[0050] In the fifth aspect, the metallating reagent is preferably
an alkyl lithium more preferably n-butyl lithium, and in the
seventh aspect, M.sup.+ preferably represents a lithium cation.
[0051] In a final aspect, the invention concerns the use of the
additive concentrate, and the use of the functionalised diblock
copolymers defined therein, to improve the cold flow behaviour of a
fuel or oil composition comprising a base fuel or oil derived from
one or more petroleum, animal, vegetable or synthetic sources, the
base fuel containing one or more n-alkyl-, iso-alkyl- or
n-alkenyl-substituted compounds, and particularly one or more
n-alkanes as hereinafter described, exhibiting a tendency to
crystallise from the base fuel or oil in cold storage or use
thereby adversely affecting the cold flow behaviour of the base
fuel or oil.
[0052] The invention will now be described in more detail as
follows.
The Additive Concentrate of the First Aspect
[0053] In accordance with the first aspect, the present invention
provides an additive concentrate comprising the functionalized
diblock copolymer defined herein in admixture with an organic
liquid miscible in fuel or oil. The term `in admixture with` as
used herein means that the copolymer and organic liquid have been
physically mixed together to provide a solution or dispersion of
the polymer in the organic liquid, the latter functioning as a
solvent or dispersing medium for the copolymer. Such liquids are
sometimes collectively termed `carrier fluids` in the art and
assist the dispersion or dissolution of the additives they contain
or oil, when the additive concentrate is blended into the base fuel
or oil. Examples of suitable liquids include hydrocarbon solvents
such as naphtha, kerosene, diesel and heater oil, aromatic
hydrocarbons such as those sold under the `SOLVESSO` trade name,
alcohols, ethers and other oxygenates and paraffinic hydrocarbons
such as hexane, pentane and isoparaffins. Likewise, the term
`miscible` as used herein means capable of being physically mixed
with fuel or oil to form either a solution or a dispersion in the
fuel or oil. The liquid is chosen having regard to its
compatibility with both the polymer and the fuel or oil in
question, and is a matter of routine choice for one skilled in the
art. The additive concentrate may suitably comprise 1 to 95% by
weight of organic liquid, preferably 10 to 70%, for example 25 to
60%, the remainder being the essential copolymer and any additional
additives required to fulfill different purposes within the fuel or
oil.
[0054] The essential functionalized diblock copolymer of the first
aspect of the invention comprises 2 polymeric blocks wherein:
[0055] (i) the first block consists of a chain of ethylenic
structural units, optionally interrupted by one or more structural
units derived from 1 -alkene co-monomers higher than ethylene, and
[0056] (ii) the second block comprises a chain of structural units
derived from one or more .alpha.,.beta.--unsaturated monomers
selected from styrene, substituted styrene, acrylate, methacrylate
and diene compounds, and wherein said first and second blocks of
the copolymer are terminally joined by means of the following
structural linkage:
##STR00009##
[0056] wherein each R group independently represents an alkyl or
aryl group and the R' group represents hydrogen or an alkyl group,
and wherein the aromatic ring substituent joined to the second
block is positioned meta or para to the aromatic ring substituent
joined to the first block. It is preferred that R' represents an
alkyl group.
[0057] Preferably, in the additive concentrate the first and second
blocks of the copolymer are terminally joined by means of the
structural linkage:
##STR00010##
wherein each R group independently represents an alkyl group having
from 1 to 4 carbon atoms and R' represents an alkyl group having
from 1 to 10 carbon atoms.
[0058] More preferably, in the additive concentrate, the first and
second blocks of the copolymer are terminally joined by means of
the structural linkage:
##STR00011##
wherein R' represents an alkyl group having from 1 to 4 carbon
atoms. More preferably, in the additive concentrate, R' represents
a butyl group and most preferably an n-butyl group.
[0059] In the additive concentrate of the first aspect, it is
particularly preferred that, in the copolymer, the aromatic ring
substituent joined to the second block is positioned meta to the
aromatic ring substituent joined to the first block.
[0060] In the additive concentrate of the first aspect, in order to
function most effectively in the fuel or oil, it is particularly
preferred that the first block of the copolymer consists of a
polyethylene chain.
[0061] In one preferred embodiment, the second block of the
copolymer consists of a chain of structural units derived from one
or more .alpha.,.beta.--unsaturated monomers selected from styrene,
substituted styrene, acrylate and methacrylate compounds,
[0062] More preferably, the second block of the copolymer consists
of a homo- or copolymeric chain derived from one or more acrylate
or methacrylate monomers. In particular, the (meth)acrylate monomer
or monomers selected for the second block usefully comprise one or
more (meth)acrylate compounds hearing a C.sub.4-C.sub.22 alkyl
substituent, which may be branched or straight chain alkyl.
Preferably the second block consists of a homo- or polymeric chain
derived from one or more such monomers. Examples of such monomers
are: 2-ethyl hexyl (meth)acrylate, isodecyl (meth)acrylate, t-butyl
(meth)acrylate, dodecyl (meth)acrylate, decyl(meth)acrylate, and
those with a C.sub.12-C.sub.15 chain length based on Neodol 25 from
Shell.
[0063] The second block act, in part, as a solubilising and/or
dispersing group for the copolymer.
[0064] In another preferred embodiment, the second block of the
copolymer consists of a chain of structural units derived from one
or more diene compounds. These dienes may be unhydrogenated,
hydrogenated or partially hydrogenated dienes. More preferably, the
second block of the copolymer consists of a homo- or copolymeric
chain derived from isoprene or butadiene or a mixture thereof.
[0065] In the additive concentrate of first aspect of the
invention, the first block of the copolymer preferably has a number
average molecular weight (Mn), as measured by GPC against
polystyrene standards, in the range of 500 to 20,000 g mol.sup.-1.
For optimum performance in fuel, it is preferred that the Mn of the
first block of the copolymer be in the range of 500 to 10,000 g
mol.sup.-1, more preferably 500 to 5,000 g mol.sup.-1.
The Fuel Oil Composition of the Second Aspect
[0066] The second aspect of the invention is a fuel or oil
composition comprising: [0067] (i) a base fuel or oil derived from
one or more petroleum, animal, vegetable or synthetic sources, the
base fuel containing one or more n-alkyl-, iso-alkyl or
n-alkenyl-substituted compounds exhibiting a tendency to
crystallise from the base fuel or oil in cold storage or use
thereby adversely affecting the cold flow behaviour of the base
fuel or oil, and [0068] (ii) the additive concentrate of the first
aspect, wherein the additive is present in the composition in an
amount sufficient to improve the cold flow behaviour of the base
fuel or oil during cold storage or use.
[0069] The base fuel may be a petroleum-based fuel oil, especially
a middle distillate fuel oil. Such distillate fuel oils generally
boil within the range of from 110.degree. C. to 500.degree. C.,
e.g. 150.degree. C. to 400.degree. C. The invention is applicable
to middle distillate fuel oils of all types, including the
distillates having a 90%-20% boiling temperature difference, as
measured in accordance with ASTM D-86, of 50.degree. C. or
more.
[0070] The base fuel may comprise atmospheric distillate or vacuum
distillate, cracked gas oil, or a blend in any proportion of
straight run and thermally and/or catalytically cracked
distillates. The most common petroleum distillate fuels are
kerosene, jet fuels, diesel fuels, heating oils and heavy fuel
oils. The heating oil may be a straight atmospheric distillate, or
may also contain vacuum gas oil or cracked gas oil or both. The
fuels may also contain major or minor amounts of components derived
from the Fischer-Tropsch process, Fischer-Tropsch fuels, also known
as FT fuels, include those that are described as gas-to-liquid
fuels, coal and/or biomass conversion fuels. To make such fuels,
syngas (CO+H.sub.2) is first generated and then converted to normal
paraffins and olefins by a Fischer-Tropsch process. The normal
paraffins may then be modified by processes such as catalytic
cracking/reforming or isomerisation, hydrocracking and
hydroisomerisation to yield a variety of hydrocarbons such as
iso-paraffins, cyclo-paraffins and aromatic compounds. The
resulting FT fuel can be used as such or in combination with other
fuel components and fuel types such as those mentioned in this
specification.
[0071] The second aspect of the invention is also applicable to
base fuels containing fatty acid alkyl esters made from oils
derived from animal or vegetable materials, often called biofuels
or biodiesels. Biofuels are believed by some to be less damaging to
the environment on combustion and are obtained from a renewable
source. Other forms of biofuels are also included in the invention
such as hydrogenated vegetable oil (HVO) and oil derived from
alternative sources such as algae.
[0072] Examples of base fuels derived from animal or vegetable
material are rapeseed oil, canola oil, coriander oil, soyabean oil,
cottonseed oil, sunflower oil, castor oil, olive oil, peanut oil,
maize oil, almond oil, palm kernel oil, coconut oil, mustard seed
oil, jatropha oil, beef tallow and fish oils. Further examples
include fuel oils derived from corn, jute, sesame, shea nut, ground
nut and linseed oil and may be derived therefrom by methods known
in the art. Rapeseed oil, which is a mixture of fatty acids
partially esterified with glycerol is available in large quantities
and can be obtained in a simple way by pressing from rapeseed.
Recycled oils such as used kitchen oils are also suitable.
[0073] As alkyl esters of fatty acids, consideration may be given
to the following, for example as commercial mixtures the ethyl,
propyl, butyl and especially methyl esters of fatty acids with 12
to 22 carbon atoms, for example of lauric acid, myristic acid,
palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic
acid, petroselic acid, ricinoleic acid, elaeostearic acid, linoleic
acid, linolenic acid, eicosanoic acid, gadoleic acid, docosanoic
acid or erucic acid, which have an iodine number from 50 to 150,
especially 90 to 125. Mixtures with particularly advantageous
properties are those which contain mainly, i.e. to at least 50 wt %
methyl esters of fatty acids with 16 to 22 carbon atoms and 1, 2 or
3 double bonds. The preferred alkyl esters of fatty acids are the
methyl esters of oleic acid, linoleic acid, linolenic acid and
erucic acid.
[0074] Commercial mixtures of the stated kind are obtained for
example by cleavage and esterification of animal and vegetable fats
and oils by their transesterification with lower (ca. C.sub.1 to
C.sub.6) aliphatic alcohols. For production of alkyl esters of
fatty acids it is advantageous to start from fats and oils which
contain low levels of saturated acids, less than 20%, and which
have an iodine number of less than 130. Blends of the following
esters or oils are suitable, e.g. rapeseed, sunflower, canola,
coriander, castor, soyabean, peanut, cotton seed, beef tallow etc.
Alkyl esters of fatty acids based on certain varieties of rapeseed
oil having more than 80 wt % of unsaturated fatty acids with 18
carbon atoms, are particularly suitable.
[0075] Whilst all of the above biofuels may be used as base fuels,
preferred are vegetable oil derivatives, of which particularly
preferred biofuels are alkyl ester derivatives of rapeseed oil,
cottonseed oil, soyabean oil, sunflower oil, olive oil, or palm
oil, rapeseed oil methyl ester being especially preferred. Such
fatty acid methyl esters are often referred to in the art as
FAME.
[0076] The invention is also applicable to pure biofuels. In one
embodiment therefore, the base fuel comprises essentially 100% by
weight of a fuel derived from a plant or animal source, preferably
essentially 100% by weight of fatty acid alkyl esters, most
preferably fatty acid methyl esters.
[0077] Biofuels are commonly used in combination with
petroleum-derived base fuels. The present invention is also
applicable to mixtures of biofuel and petroleum-derived base fuels
in any ratio. Such fuels are often termed "Bx" fuels where x
represents the percentage by weight of biofuel in the
biofuel-petroleum blend. Examples, include fuels where x is 2 or
above, preferably 5 or above, for example up to 10, 25, 50, or 95.
Preferably the biofuel component in such Bx base fuels comprises
fatty acid alkyl esters, most preferably fatty acid methyl
esters.
[0078] The base fuel, whether petroleum or vegetable or
animal-derived, or synthetic, preferably has a low sulphur content.
Typically, the sulphur content of the fuel will be less than 500
ppm (parts per million by weight). Preferably, the sulphur content
of the fuel will be less than 100 ppm, for example, less than 50
ppm. Fuels with even lower sulphur contents, for example less that
20 ppm or less than 10 ppm are also suitable.
[0079] Base oils useful in the context of the present invention
include those oils of lubricating viscosity, preferably selected
from natural lubricating oils, synthetic lubricating oils and
mixtures thereof. The base oil may range in viscosity from light
distillate mineral oils to heavy lubricating oils such as gasoline
engine oils, mineral lubricating oils and heavy duty diesel oils,
and marine lubricants. Generally, the viscosity of the base oil
ranges from about 2 centistokes to about 40 centistokes, especially
from about 4 centistokes to about 20 centistokes, as measured at
100.degree. C.
[0080] Natural base oils include animal oils and vegetable oils
(e.g., castor oil, lard oil); liquid petroleum oils and
hydrorefined, solvent-treated or acid-treated mineral oils of the
paraffinic, naphthenic and mixed paraffinic-naphthenic types. Base
oils of lubricating viscosity derived from coal or shale also serve
as useful base oils.
[0081] Synthetic base lubricating oils include hydrocarbon oils and
halo-substituted hydrocarbon oils such as polymerized and
interpolymerized olefins (e.g., polybutylenes, polypropylenes,
propylene-isobutylene copolymers, chlorinated polybutylenes,
poly(1-hexenes), poly(1-octenes), poly(1-decenes)); alkylbenzenes
(e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,
di(2-ethylhexyl)benzenes); polyphenyls (e.g., biphenyls,
terphenyls, alkylated polyphenols); and alkylated diphenyl ethers
and alkylated diphenyl sulfides and derivative, analogs and
homologs thereof. Also useful are synthetic oils derived from a gas
to liquid process from Fischer-Tropsch synthesized hydrocarbons,
which are commonly referred to as gas to liquid, or "GTL" base
oils.
[0082] Alkylene oxide polymers and interpolymers and derivatives
thereof where the terminal hydroxyl groups have been modified by
esterification, etherification, etc., constitute another class of
known synthetic base oils. These are exemplified by polyoxyalkylene
polymers prepared by polymerization of ethylene oxide or propylene
oxide, and the alkyl and aryl ethers of polyoxyalkylene polymers
(e.g., methyl-polyiso-propylene glycol ether having a molecular
weight of 1000 or diphenyl ether of poly-ethylene glycol having a
molecular weight of 1000 to 1500); and mono- and polycarboxylic
esters thereof, for example, the acetic acid esters, mixed
C.sub.3-C.sub.8 fatty add esters and C.sub.13 oxo acid diester of
tetraethylene glycol.
[0083] Another suitable class of synthetic base oils comprises the
esters of dicarboxylic acids (e.g., phthalic acid, succinic acid,
alkyl succinic acids and alkenyl succinic acids, maleic acid,
azelaic acid, suberic acid, sebasic acid, fumaric acid, is adipic
acid, linoleic acid dimer, malonic acid, alkylmalonic acids,
alkenyl malonic acids) with a variety of alcohols (e.g., butyl
alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol,
ethylene glycol, diethylene glycol monoether, propylene glycol).
Specific examples of such esters includes dibutyl adipate,
di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate,
diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl
phthalate, dicicosyl sebacate, the 2-ethylhexyl diester of linoleic
acid dimer, and the complex ester formed by reacting one mole of
sebacic acid with two moles of tetraethylene glycol and two moles
of 2-ethylhexanoic acid.
[0084] Esters useful as synthetic base oils also include those made
from C.sub.5 to C.sub.12 monocarboxylic acids and polyols and
polyol esters such as neopentyl trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol,
[0085] Silicon-based base oils such as the polyalkyl-, polyaryl-,
polyalkoxy- or polyaryloxysilicone oils and silicate oils comprise
another useful class of synthetic lubricants; such oils include
tetraethyl silicate, tetraisopropyl silicate,
tetra-(2-ethylhexyl)silicate,
tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl)
3D silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane,
poly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other
synthetic lubricating oils include liquid esters of
phosphorous-containing acids (e.g., tricresyl phosphate, trioctyl
phosphate, diethyl ester of decylphosphonic acid) and polymeric
tetrahydrofurans.
[0086] Base oils of lubricating viscosity may comprise a Group I,
Group II or Group III, base stock or base oil blends of the
aforementioned base stocks. Preferably, the oil is of lubricating
viscosity and is a Group II or Group III base stock, or a mixture
thereof, or a mixture of a Group I base stock and one or more a
Group II and Group III. Preferably, a major amount of the oil of
lubricating viscosity is a Group II, Group III, Group IV or Group V
base stock, or a mixture thereof. The base stock, or base stock
blend preferably has a saturate content of at least 65%, more
preferably at least 75%, such as at least 85%. Most preferably, the
base stock, or base stock blend, has a saturate content of greater
than 90%. Preferably, the base oil or oil blend will have a sulfur
content of less than 1%, preferably less than 0.6%, most preferably
less than 0.4%, by weight. Equally, the base oil or base oil blend
may be hydrodesulphurised to sulphur content of very low levels,
typically 1500 ppm by weight or less, preferably 15 ppm by weight
or less.
[0087] Preferably the volatility of the base oil or oil blend, as
measured by the Noack volatility test (ASTM D5880), is less than or
equal to 30%, preferably less than or equal to 25%, more preferably
less than or equal to 20%, most preferably less than or equal 16%.
Preferably, the viscosity index (VI) of the oil or oil blend is at
least 85, preferably at least 100, most preferably from about 105
to 140.
[0088] Definitions for the base stocks and base oils suitable for
use in this invention are the same as those found in the American
Petroleum Institute (API) publication "Engine Oil Licensing and
Certification System", Industry Services Department, Fourteenth
Edition, December 1996, Addendum 1, December 1998. Said publication
categorizes base stocks as follows: [0089] a) Group I base stocks
contain less than 90 percent saturates and/or greater than 0.03
percent sulfur and have a viscosity index greater than or equal to
80 and less than 120 using the test methods specified in Table 1.
[0090] b) Group II base stocks contain greater than or equal to 90
percent saturates and less than or equal to 0.03 percent sulfur and
have a viscosity index greater than or equal to 80 and less than
120 using the test methods specified in Table 1. [0091] c) Group
III base stocks contain greater than or equal to 90 percent
saturates and less than or equal to 0.03 percent sulfur and have a
viscosity index greater than or equal to 120 using the test methods
specified in Table 1. [0092] d) Group IV base stocks are
polyalphaolefins (PAO). [0093] e) Group V base stocks include all
other base stocks not included in Group I, II, III, or IV.
[0094] The additive concentrate of the first aspect is added to the
base fuel or oil in an amount sufficient to improve the cold flow
behaviour of the base fuel or oil during cold storage or use. In
practice, the resulting amount of essential copolymer present in
the base fuel or oil in question may vary with the type of fuel or
oil, and the cold flow behavior desired, and will be determined by
the individual circumstances and needs. Suitably however, the
additive concentrate will be added to base fuels in such an amount
that it provides the essential copolymer in an amount of between 10
and 5,000, preferably between 10 and 1,000, more preferably between
50 and 500 ppm by weight, based on the weight of the fuel.
[0095] Also suitably the additive concentrate will be added to base
oils in such an amount that it provides the essential copolymer in
an amount of between 10 and 5,000 preferably between 10 and 1,000,
more preferably between 50 and 500 ppm by weight, based on the
weight of the oil.
[0096] With regard to the second aspect of the invention,
improvement of the cold flow behaviour of a fuel or oil will be
understood by those skilled in the art to refer to the ability of
the fuel or oil to flow, to be pumped or to pass through filter
media when cooled to low ambient temperatures such as may be
experienced by vehicles operating in regions with cold climates.
For example, tests such as the Cold Filter Plugging Point test
(CFPP) and the Pour Point test (PP) are widely used in the industry
to determine fuel and/or oil operability at low temperatures. These
tests are designed to determine filterability and/or flowability at
temperatures wherein the tendency towards crystallization of
n-alkyl, iso-alkyl or n-alkenyl substituted compounds, and
particularly n-alkanes, is exhibited. Improvements in this cold
flow behavior due to the presence of the additive of the invention
can be readily determined by comparative tests of the fuel with or
without the additive in question.
[0097] However, the present invention in all its aspects is
particularly applicable to those base fuels or oils that contain
one or more n-alkanes or n-alkenes, preferably one or more
n-alkanes, in particular one or more alkanes containing at least 20
carbon atoms, and more preferably one or more alkanes containing at
least 24 carbon atoms, such as at least 26, 27, 28, 29 or 30 carbon
atoms. Such compounds exhibit a well-known tendency to crystallise
from the base fuel or oil in cold storage or use, thereby adversely
affecting the cold flow behaviour of the base fuel or oil. Base
fuels and oils containing such compounds thus particularly suffer
from the problem addressed by this invention and are particularly
suitable to treatment from the additive described herein, and
compositions containing such base fuels are particularly preferred
under the second aspect of the invention.
[0098] More preferably, these preferred compositions of the second
aspect comprise a base fuel which is a diesel fuel or heating oil,
being either a petroleum-derived base fuel, or a mixture of
petroleum-derived base fuel and vegetable-derived base fuel, or a
vegetable-derived base fuel. Most preferably, the compositions of
the second aspect comprise a base fuel which is a diesel fuel being
either a petroleum-derived base fuel, or a mixture of
petroleum-derived base fuel and vegetable-derived base fuel,
containing one or more n-alkanes containing at least 20 carbon
atoms, and more preferably containing at least 25 carbon atoms,
such as at least 26, 27, 28, 29 or 30 carbon atoms.
The Method of the Third Aspect
[0099] The third aspect of the invention provides a method of
improving the cold flow behaviour of a fuel or oil composition
derived from one or more petroleum, animal, vegetable or synthetic
sources and containing one or more n-alkyl- or iso-alkyl or
n-alkenyl-substituted compounds exhibiting a tendency to
crystallise from the base fuel or oil in cold storage or use
thereby adversely affecting the cold flow behaviour of the base
fuel or oil, the method comprising: [0100] (i) determining the cold
flow behaviour of the base fuel or oil in question and the
improvement that is required; [0101] (ii) determining the amount of
the additive concentrate of the first aspect necessary to effect
the desired improvement in cold flow behaviour; and [0102] (iii)
treating the base fuel or oil with that amount of the additive
concentrate.
[0103] In the method aspect of the invention, the base fuel and
oil, and the additive concentrate, are those defined in relation to
the first and second aspects above.
[0104] The method involves determining the necessary amount of
additive for a given base fuel or oil in a given circumstance. In
practice, the desired cold flow properties of a fuel or oil are
usually specified by the fuel or oil manufacturer, in relation to
desired performance in the industry test(s) adopted by that
manufacturer as most relevant to the environment the fuel or oil is
likely to meet. These performance targets, when compared to the
performance of the base fuel alone, provide a clear target for the
necessary improvement which the additive must achieve in a given
case. It is a matter of normal skill in the art to thereafter
determine the amount of additive that must be used to achieve that
desired improvement, through comparative experiments in those
test(s) specified by the manufacturer.
The Funtionalised Diblock Copolymer of the Fourth Aspect
[0105] The preferred embodiments of the copolymer of the fourth
aspect of the invention are those defined in relation to any of the
other aspects of the invention. For brevity these are not
reproduced verbatim.
The Process of the Fifth Aspect
[0106] The fifth aspect of the invention is a process for
manufacture of a functionalised diblock copolymer comprising 2
polymeric blocks wherein: [0107] (i) the first block consists of a
chain of ethylenic structural units, optionally interrupted by one
or more structural units derived from 1-alkene co-monomers higher
than ethylene, and [0108] (ii) the second block comprises a chain
of structural units derived from one or more
.alpha.,.beta.--unsaturated monomers selected from styrene,
substituted styrene, acrylate, methacrylate and diene compounds,
and wherein said first and second blocks of the copolymer are
terminally joined by means of the following structural linkage:
##STR00012##
[0108] wherein each R group independently represents an alkyl or
aryl group and R' represents hydrogen or an alkyl group, and
wherein the aromatic ring substituent joined to the second block is
positioned meta or para to the aromatic ring substituent joined to
the first block; the process comprising the following steps: [0109]
a) in a first step, polymerising ethylene, and optionally one or
more 1-alkene co-monomers higher than ethylene, in the presence of
a metallocene catalyst system to form a first polymer block, being
a chain consisting of ethylenic structural units optionally bearing
pendent alkyl groups originating from 1-alkene comonomer(s), the
reaction being carried out in solution at a temperature of at least
50.degree. C. in the presence of a compound of the formula (I):
##STR00013##
[0109] in a reaction vessel pressurised with hydrogen gas, wherein,
in the course of the reaction, the compound (I) is terminally
incorporated onto the first polymer block resulting in the
formation of a terminally unsaturated intermediate of the formula
(II):
##STR00014## [0110] b) in a second step, recovering the
intermediate (II) from the reaction mixture of the first step; and
[0111] c) in a third step, reacting the intermediate (II) at its
terminal double bond in a subsequent polymerisation reaction to
form a second polymer block, so yielding a diblock polymer of the
structure defined above.
[0112] In the process aspect of the invention, step c) is
preferably an anionic polymerisation reaction, wherein the terminal
double bond of the intermediate of formula (II) is reacted with a
metallating reagent to form an anion which initiates polymerisation
therefrom upon the addition of one or more
.alpha.,.beta.--unsaturated monomers selected from styrene,
substituted styrene, acrylate, methacrylate and diene
compounds.
[0113] The preferred embodiments of the process of the fifth aspect
of the invention are those giving rise to the preferred embodiments
of the functionalised block copolymer defined in relation to the
other aspects of the invention. For brevity these preferred
polymers are not reproduced verbatim.
[0114] The first step a) of the process proceeds at a reaction
medium temperature of at least 50.degree. C., preferably at least
55.degree. C., and more preferably at least 58'C, such as at least
60.degree. C. This minimum temperature avoids compound (I)
homopolymerising significantly in the presence of the metallocene
catalyst, and thus avoids an unwanted competing reaction.
Preferably, the reaction temperature is maintained within the range
of 55.degree. C. to 90.degree. C., more preferably in the range of
58.degree. C. to 80.degree. C.
[0115] The first step a) of the process is also essentially
conducted in a vessel under pressure in the presence of hydrogen
gas. Hydrogen is required to enable the necessary reaction to take
place between the growing polyethylenic chain, the metallocene
catalyst and the compound (I), leading to the terminal insertion of
the compound (I) on the polyethylenic chain. Maintaining the
pressure of the system during this step is also important to
obtaining good productivity in the reaction and effective molecular
weight control of the first polymer block.
[0116] Preferably, the partial pressure of hydrogen in the reaction
vessel is set to between 170 and 280 kPa, preferably in the range
of 185 to 242 kPa. Also preferably, the partial pressure of
ethylene in the reaction vessel is preferably set to between 35 and
440 kPa, more preferably in the range of 70 to 415 kPa, most
preferably in the range of 80 to 285 kPa.
[0117] More preferably, the partial pressure of hydrogen in the
reaction vessel is set to between 185 to 242 kPa and the partial
pressure of ethylene is set to between 80 and 285 kPa.
[0118] Suitable metallocene catalysts comprise a Transition Metal,
particularly a metal from group IV of the periodic table such as
Ti, Zr or Hf, with one or more ligands such as cyclopentadienyl
("Cp"), substituted cyclopentadienyl (including indenyl, fluorenyl
and their derivatives), and bridged variants of the above.
Additional ligands may be coordinated or bonded to the metal by
heteroatoms such as N, O, S or P and may include bridges to Cp-type
ligands as above.
[0119] Such catalysts are normally synthesised and stored as a
metal dichloride/dialkyl (e.g. dibenzyl) or
mono-alkyl-mono-chloride species ("pre-catalyst"). This is
activated in solution by addition of a co-catalyst, generally
methylaluminoxane (MAO), but alternatively a combination of a boron
containing species such as Ph.sub.3C+B(C.sub.6F.sub.5).sub.4- and a
trialkylaluminium species such as i-(C.sub.4H.sub.9).sub.3Al. In
practice, the choice of metallocene catalyst will be exercised by
the skilled chemist in accordance with conventional principles.
Amongst relevant principles, the essential presence of hydrogen in
the reaction naturally dictates that the catalyst chosen should be
one whose function is not impaired by hydrogen.
[0120] Examples of such catalysts include C.sub.2MCl.sub.2,
Cp*.sub.2MCl.sub.2, Flu(Ph.sub.2Me)CpMCl.sub.2, and
Cp(Me).sub.4(Me.sub.2Si)NtBuMCl.sub.2, wherein M represents a
transition metal, Most preferred catalysts are catalysts in which M
represents zirconium. The most preferred catalyst. is
Cp.sub.2ZrCl.sub.2 and the most preferred co-catalyst is MAO.
[0121] The following is a working example of the first step of the
process.
Working Example 1--Step a) of the Process Preparation of Compound
(II)
[0122] A 250 ml stainless steel Parr reactor with internal cooling
coil was dried under vacuum at 100.degree. C. for 1 hour before
addition of a comonomer solution consisting of toluene (50 ml),
1,3-diisopropenylbenzene (30 ml, 0.175 mol--compound (1)) and MAO
solution (3 ml, 1800 equivalents) via cannula with the reactor
initially heated to 50.degree. C. The reactor was purged for 5 min
with hydrogen (240 kPa) before the addition of ethylene (85 kPa).
Once ethylene uptake had stabilised, a toluene solution of
metallocene catalyst Cp.sub.2ZrCl.sub.2 (2.5.times.10.sup.-6 mol)
prepared in the glovebox was injected using an overpressure of
argon. After catalyst addition, the temperature and gas uptake were
continuously monitored. The reaction temperature was maintained at
60.degree. C. The reaction was stopped after 15 min by careful
addition of methanol (2.times.10 ml). The polymer product was
precipitated by pouring into a solution of 5% HCl in methanol (600
ml) with stirring for 1 h. The product was recovered by filtration
and washed with methanol, and once dry washed again with
tetrahydrofuran (200 ml). The polymer product,
1,3-diisopropenylbenzene terminated polyethylene (compound (II),
being PE-t-DIB) was dried by heating to 70.degree. C. in vacua for
24 h, giving a yield of 1655 g.
[0123] The productivity of the reaction was 4235 kg
(Polymer)/(mol[cat.]h). The 1,3-DIB content of the resulting
polymer (compound (II)) was 2.54 mol % and it had an Mw of 3269 g
mol.sup.-1, an M.sub.n of 1893 g mol.sup.-1, and Dispersity (PDi)
of 1.73, as measured by high temperature GPC was performed in
1,2,4-trichlorobenzene at 160.degree. C. at a flow rate of 1 ml/min
on a Polymer Labs PL220 fitted with a 5 cm PLgel guard column (5
.mu.M), and two PLgel 30 cm Mixed-D columns (5 .mu.M). Calibration
was achieved using Polymer Labs PSM Ensivial polystyrene standards.
The molecular weight is determined by comparing the retention time
of the polymer with that of the calibration curve at that retention
time.
[0124] The characterisation of compound II, to confirm the desired
terminal functionalisation structure is obtained, can be conducted
by nuclear magnetic resonance spectroscopy.
[0125] For example, NMR spectra can he recorded on Bruker DPX400
and DPX500 spectrometers, wherein .sup.1H and .sup.13C NMR spectra
are referenced internally using the solvent resonances relative to
tetramethylsilane. Routine NMR assignments (including polymer
samples) can be confirmed by .sup.1H-.sup.1H (COSY),
.sup.13C-.sup.1H (HMQC) and .sup.13C-.sup.1H (HMBC) correlation
experiments where necessary.
[0126] In particular, to confirm the terminal insertion of the
compound (I), .sup.1H NMR spectroscopy can be employed. For
example, shown in the attached FIG. 1 is a typical .sup.1H NMR
spectra for a compound (II) as produced by the above process step
a), employing ethylene as the constituent of the first polymer
block, and 1,3-diisopropenylbenzene ("1,3-DIB") as compound I.
Determination of the amount of terminal insertion is achieved by
comparison of the spectroscopic peaks for a methyl group at one end
of the polyethylene chain which has three protons (labelled A in
the figure), and a single proton on the benzylic carbon of the
1,3-DIB molecule remaining after step a) of the reaction (labelled
B in the figure). Any 1,3-DIB incorporated in-chain would not have
a proton on this carbon, and thus this proton resonance serves to
distinguish terminal insertion of the 1,3-DIB.
[0127] The .sup.1H NMR peaks associated with these protons (A and
B) have chemical shifts of 0.91 ppm and 2.71 ppm respectively
(chemical shifts are measured against the residual solvent signal
in d.sub.2-TCE at 5.94 ppm). Comparing the integrals of these two
peaks gives the amount of terminal insertion by 1,3-DIB. As can be
seen for example in the spectrum shown, an integrals ratio of the
respective peaks of 3:1 (A:B) indicates that essentially each
polyethylene chain is terminally functionalised by the residue from
the 1,3-DIB.
[0128] An advantage of the process of the invention is in securing
a high degree of terminal functionalization of the first block, as
determined by the above spectroscopic method. Thus, further
examples of step a) of the process and the results achieved are
shown below:
Further Worked Examples 2 to 5 of the Process Step a) and Compound
(II)
[0129] Following the above worked example but with the process
conditions in step a) adjusted as shown in the table below, further
examples of compound (II) were conducted as follows:
TABLE-US-00001 Hydrogen Ethylene Reaction Productivity Co- pressure
pressure Temperature (kg polymer/ Example no monomer Monomer (kPa)
(kPa) (.degree. C.) mol[M] h) 2 1,3-DIB ethylene 240 285 62 13754 3
1,3-DIB ethylene 240 285 61 13758 4 1,3-DIB ethylene 240 285 63
13307
[0130] In each case, the reaction resulted in essentially complete
terminal functionalization of the polyethylenic chains by
co-monomer compound (I), so forming compound (II) to a highly
specific degree. The high productivity achieved in the reaction is
also shown in the table.
[0131] The compound II can be isolated as demonstrated in the
worked example 1, or by other means of recovery known to the
polymer chemist.
[0132] The preferred embodiments of the process, and of the
resulting compound II, are those resulting from the preferred forms
of compound (I) described above, and in particular from those
preferred compounds in combination with a first block consisting of
polyethylene.
[0133] Thus in the process and compound (II) aspects of the
invention, the originating compound (I) preferably has the
structure:
##STR00015##
wherein each R group independently represents an alkyl group having
from 1 to 4 carbon atoms.
[0134] More preferably, the originating compound (I) has the
structure:
##STR00016##
[0135] Most preferably, in the above preferred embodiments of
compound (I), the aromatic ring substituents are positioned meta to
each other.
[0136] The third step c) of the process of the invention involves
the formation of the second block. Preferably, the third step c) is
an anionic polymerisation reaction, wherein the terminal double
bond of the compound of formula (II) is reacted with a metallating
reagent to form an anion which initiates polymerisation therefrom
upon the addition of one or more .alpha.,.beta.--unsaturated
monomers bearing one or more functional groups selected from
styrene, substituted styrene, acrylate, methacrylate and diene
compounds.
[0137] Preferably, in the anionic polymerisation, the metallating
agent is an alkyl metal compound R'M and the compound (II) has the
structure:
##STR00017##
wherein each R group independently represents an alkyl group having
from 1 to 4 carbon atoms; and wherein, in the course of the third
reaction step c), the alkyl group R' of the alkyl metal compound
inserts onto the less-substituted carbon of the double bond, giving
rise to a reactive anionic intermediate having the structure of the
formula (III):
##STR00018##
wherein R' represents the inserted alkyl group originating from the
alkyl metal compound, .sup.(-) represents the metallated
carbanionic site from which the anionic polymerisation of the third
reaction step thereafter proceeds, and M.sup.(+) represents the
metal cation originating from the metal M of the alkyl metal
compound,
[0138] In this process, the metallating reagent preferably
comprises n-butyl lithium or sec-butyl lithium, such that M.sup.(+)
in the above formula represents a lithium cation and R' represents
n-butyl or sec-butyl.
[0139] Particularly preferred is a process wherein the compound
(II) has the structure:
##STR00019##
and the metallating reagent comprises n-butyl lithium.
[0140] Further embodiments of the invention include the isolated
intermediate compound of the formula (II):
##STR00020##
wherein each R group independently represents an alkyl or aryl
group, and wherein the aromatic ring substituent C(R).dbd.CH.sub.2
is positioned meta or para to the substituent joined to the first
block; and the anionic intermediate of the formula (III):
##STR00021##
wherein each R group independently represents an alkyl or aryl
group and wherein the aromatic ring substituent
--C.sup.(-)(R)--CH.sub.2(R') is positioned meta or para to the
aromatic ring substituent joined to the first block; wherein R'
represents an alkyl group and M.sup.+represents a metal cation, and
C.sup.(-) represents a metallated carbanionic site.
[0141] Preferably, in the compound (II) and the anionic
intermediate each R group independently represents an alkyl group
having from 1 to 4 carbon atoms. More preferably, each R group
independently represents a methyl group. Also preferably, R'
represents n-butyl, Most preferably, each R group independently
represents a methyl group and R' represents n-butyl.
[0142] Equally, in compound (II) and the anionic intermediate it is
preferred that the two aromatic ring substituents are positioned
meta to each other.
[0143] In a preferred embodiment, compound (II) and the anionic
intermediate have a first block having a number average molecular
weight (Mn), as measured by GPC against polystyrene standards, in
the range of 500 to 20,000 g mol.sup.-1 and preferably in the range
of 500 to 10,000 g mol.sup.-1, more preferably 500 to 5,000 g
mol.sup.-1. More preferably, the first block consists of a
polyethylene chain,
Working Example 2--Step c) of the Process--Anionic
Polymerisation
[0144] In a typical anionic polymerisation example, a
Schlent(vessel equipped with a stirrer bar was charged with
1,3-diisopropenylbenzene terminated polyethylene (compound (II),
being PE-t-DIB) (0.5 g, 3.6.times.10.sup.-4 mol) before cyclohexane
(50 ml) and n-butyllithium solution (2 ml, 5.times.10.sup.-3 mol)
were added via cannula. The reaction mixture was stirred and heated
to 70.degree. C. using an aluminium heating block for 3 h. The
reaction was allowed to cool and the thus lithiated polymer
intermediate (red) was allowed to settle before a filter cannula
was used to remove the solvent and excess n-butyllithium,
[0145] The polymer intermediate was washed twice with cyclohexane
(2.times.50 ml) and cyclohexane (50 ml) and styrene (2 ml,
1.7.times.10.sup.-2 mol) added at ambient temperature with
stirring. After 19 h the reaction was terminated by addition of
methanol (10 ml) and the precipitated diblock copolymer was
filtered and dried overnight in vacuo for 24 h. The yield was 2.692
g and the final polymer characterised as M.sub.W of 81877 g
mol.sup.-1, M.sub.n of 47440 g mol.sup.-1, and a Dispersity of 1.73
as measured by the GPC method described previously in relation to
the worked example of step a).
[0146] The effectiveness of the functionalised diblock copolymers
described herein in improving the cold flow behaviour of fuels and
oils is illustrated hereafter, by reference to the performance of a
range of synthesised block copolymers as cold flow improvers for
diesel fuel.
Worked Example 3--Synthesis of Diblock Copolymers and Performance
As Fuel Additives
[0147] Based on the general worked example above, examples of
diblock copolymers were made as shown in the table below, in each
case starting from the specified compound (II) produced in step a)
of the reaction as shown.
[0148] In each case, the diblock polymer produced was thereafter
tested for its ability to improve (i.e. lower) the cold filter
plugging point temperature ("CFPP" temperature) of a base diesel
fuel having an untreated CFPP temperature of each case, the polymer
was added to the base fuel via the preparation of an additive
concentrate of the invention, involving the physical mixing of the
polymer and organic carrier liquid (aromatic solvent) using a
laboratory rotary blender, and thereafter doped into the fuel in
varying amounts to determine the fuel's response to the additive in
each case.
[0149] As can be seen from the results, the polymers of the
invention, when used as additives for diesel fuel, brought about
significant improvements in the cold flow behaviour over the base
fuel, as evidenced by the depression of the cold filter plugging
point (CFPP) temperature in the range of tests shown. As a result,
the treated fuels are less likely to give rise to problems of
filter blocking after periods of cold storage, or during use at
cold temperatures.
Results (base fuel CFPP=-10.degree. C.)
TABLE-US-00002 Monomer Treat rate of CFPP Com- for anionic product
in temper- pound Metallating polymer- Product diesel fuel ature
(II) reagent isation formed (ppm, wt/wt) (.degree. C.) PE-t- n-BuLi
styrene PE-DIB- 200 -13 DIB* PS 300 -17 400 -16 PE-t- n-BuLi
tert-butyl PE-DIB 200 -17 DIB* styrene tBS 300 -20 PE-t- n-BuLi
Tert-butyl PE-DIB- 200 -17 DIB* methacrylate tBMA 300 -16 400 -14
PE-t- n-BuLi isoprene PE-DIB- 200 -17 DIB* PI 300 -18 400 -20
*polyethylene terminally functionalised with 1,3-DIB
(diisopropenylbenzene)
[0150] From the results, it is evident that the diblock copolymer
functions in its own right as a cold flow improver.
[0151] The determination of the improvement at a range of treat
rates allows the skilled person to draw conclusions about the
necessary amount of each additive required to provide optimum (or
other target) performance when employing the method and use of the
invention.
* * * * *